Association and decontamination of Bacillus spores in a simulated drinking water system.
The objective of this work was to elucidate the disinfectant susceptibility of Bacillus anthracis Sterne (BA) and a commercial preparation of Bacillus thuringiensis (BT) spores associated with a simulated drinking water system. Biofilms composed of indigenous water system bacteria were accumulated on copper and polyvinyl chloride (PVC) pipe material surfaces in a low-flow pipe loop and uniformly mixed tank reactor (CDC biofilm reactor). Application of a distributed shear during spore contact resulted in approximately a 1.0 and 1.6 log10 increase in the number of spores associated with copper and PVC surfaces, respectively. Decontamination of spores in both free suspension and after association with biofilm-conditioned pipe materials was attempted using free chlorine and monochloramine. Associated spores required 5- to 10-fold higher disinfectant concentrations to observe the same reduction of viable spores as in suspension. High disinfectant concentrations (103 mg/L free chlorine and 49 mg/L monochloramine) yielded less than a 2-log10 reduction in viable associated spores after 60 min. Spores associated with biofilms on copper surfaces consistently yielded higher Ct values than PVC.
Morrow
J B
JB
National Institute of Standards and Technology, Biochemical Science Division, 100 Bureau Drive MS 8312, Gaithersburg, MD 20899-8310, USA. jayne.morrow@nist.gov
Almeida
J L
JL
Fitzgerald
L A
LA
Cole
K D
KD
D001408:Bacillus anthracis / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D001413:Bacillus thuringiensis / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D019149:Bioreactors; D003300:Copper; D004202:Disinfectants / Q000494:pharmacology; D011143:Polyvinyl Chloride; D013171:Spores, Bacterial / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D018508:Water Purification / Q000379:methods; D014881:Water Supply / Q000592:standards*
D004202:Disinfectants; D003300:Copper; D011143:Polyvinyl Chloride